A single final question can shake the certainty gained by answering to many other previous questions.
So, if we are put to doubt about the final target of one of our journeys, we are ready to doubt the righteousness of our previous steps made until then, though they were correct answers to some questions regarding that journey.
The final question draws its power over the preliminary questions and answers from our constant incapacity of thinking about the end of our actions.
Even if we are always confronted with many endings of actions and things, we are not really acquainted with a definitive ending. Our life and our mind can always to add something to an ended action or thought. All of them are prolonged in a way or another in virtue of our ongoing life and thought.
Therefore, since we do not possess the knowledge of a total ending, a final question meant to doubt an entire action or thought is received as one that affects all the previous ended steps. All of them are considered as borrowing their endings to such questionable final end.
It is the case of the question about the meaning of life, too. When we are forced to answer to it, we feel uncertain about all of our life, in spite of the fact that it is composed by a long series of correct answers.
When the religions speak about a divine meaning of life, it is not hard for them to make someone to believe that all his life should be set to follow such a meaning. For the end of the human life and of the world which are professed by religions overwhelm all his knowledge about endings. He easily renounces to those partial endings of his actions and thoughts, though they had created his identity and life.